1. Field of the Invention
The present invention relates to an apparatus for cutting a sheet-like member such as an adhesive tape applied to a surface of a semiconductor wafer at the periphery of said semiconductor wafer.
2. Description of the Prior Art
In the process of manufacturing a semiconductor device (chip), there is a step of grinding a semiconductor wafer such as a silicon wafer down to a predetermined thickness. Generally in this step, while the surface of a semiconductor wafer is chucked to a chuck table by vacuum suction, the back surface of the wafer is ground. In many cases, however, an element pattern is formed on the surface of the semiconductor wafer, so that chucking the said wafer surface directly onto the chuck table by vacuum suction leads to such inconvenience as damaging the element pattern or getting the surface contaminated with silicon dusts generated while grinding. As a consequence, it is a usual measure to apply an adhesive (sticky) tape onto the surface of the semiconductor wafer and thereby protect the wafer surface.
An adhesive tape, which is applied onto the wafer surface for the above purpose, must be cut along the outline of the semiconductor wafer, but such cutting has been conventionally carried out mechanically by use of a metallic blade.
Such a mechanical method of cutting, however, has caused the following problems.
When an adhesive tape is mechanically cut along the periphery of a semiconductor wafer by a cutting blade such as a metallic blade, this cutting blade is unavoidably pressed against the periphery of the semiconductor wafer with a considerably great strength. A peripheral portion of the semiconductor wafer may, as a consequence, be broken off by the cutting blade. In addition, it is another shortcoming that the wear of the said cutting blade is substantial due to the inevitable imposition of considerably large cutting resistance upon the cutting blade.
Furthermore, the outline of a semiconductor wafer generally is not a full circle and, in particular, may wave a straight portion called an orientation flat in the outer periphery thereof, as will be described later. By the method of mechanical cutting with a conventional blade, therefore, it is difficult to automatically move the cutting blade along the outline of the semiconductor wafer, so that the cutting operation of the adhesive tape had to be done manually by manpower.
Among various semiconductor wafers, particularly, those of such material as GaP or GaAs, some are broken off more easily than one made of silicon, and they also vary in outlines, thus causing an even bigger problem.